Using a cheap AVR has been discussed quite a lot. A quality amp will only reproduce the low quality signal from the cheap AVR, not improve it. A quality amp needs a quality front end to perform to its maximum potential. I second elevick's recommendation for the Outlaw Audio 975. No bells and whistles, but high quality sound.
http://www.soundandvision.com/content/outlaw-model-975-surround-processor
http://hometheaterreview.com/outlaw-audio-model-975-71-av-surround-sound-processor-reviewed/